Technical Abstract:
Venom allergen-like proteins (VAPs) are members of the SCP/Tpx-1/Ag5/PR-1/Sc7 family of eukaryotic secreted proteins. We have identified a VAP gene (designated GrVAP-1) from the potato cyst nematode Globodera rostochiensis. The GrVAP-1 gene contains an open reading frame (660 bp) encoding a putative secreted protein that contains a SCP-like domain and a cysteine-rich C-terminus. Southern blot analysis indicated the presence of multiple copies of the GrVAP-1 gene in the G. rostochiensis genome. The GrVAP-1 genomic DNA contains three introns with sizes ranging from 48 to149 bp. In-situ mRNA hybridization showed the transcript of GrVAP-1 accumulated exclusively within the subventral esophageal gland cells of both preparasitic second-stage juvenile (J2) and parasitic stages of G. rostochiensis. RT-PCR analysis revealed that the GrVAP-1 gene was highly expressed in both preparastic J2 and parasitic stages, but its expression was low in the egg stage. In vitro and in vivo RNA interference experiments are underway to investigate a potential role of GRVAP-1 in nematode parasitism of host plants.